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The  early  history  of  the  Airplaneo 


~7/fe 

EARLY  Ht/TORY 

•     Or  fne     •       • 

AIRPLANE 


OAYTON-WRIGHT  AIRPLANE  Oa 

OAYTON*OHIO 


LIBRARY 

UNIVERSITY  OF  CALIFORNIA 
DAVIS 


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The  IDright  Brothers'  Aeroplane 


By  OrvilU  and  Wilbur  Wright 


^  m  I  >HOUGH  the  subject  of  aerial 
Y  l"^  navigation  is  generally  consid- 
\^j  J  ered  new,  it  has  occupied  the 
^^  minds  of  men  more  or  less 
from  the  earliest  ages.  Our  personal  in- 
terest in  it  dates  from  our  childhood 
days.  Late  in  the  autumn  of  1878  our 
father  came  into  the  house  one  evening 
with  some  object  partly  concealed  in  his 
hands,  and  before  we  could  see  what  it 
was,  he  tossed  it  into  the  air.  Instead  of 
falling  to  the  floor,  as  we  expected,  it  flew 
across  the  room,  till  it  struck  the  ceiling, 
where  it  fluttered  awhile,  and  finally 
sank  to  the  floor.  It  was  a  little  toy, 
known  to  scientists  as  a  "helicoptere," 
but  which  we,  with  sublime  disregard  for 
science,  at  once  dubbed  a  "bat."  It  was 
a  light  frame  of  cork  and  bamboo,  cov- 
ered with  paper,  which  formed  two 
screws,  driven  in  opposite  directions  by 
rubber  bands  under  torsion.  A  toy  so 
delicate  lasted  only  a  short  time  in  the 
hands  of  small  boys,  but  its  memoiy  was 
abiding. 

Several  years  later  we  began  building 
these  helicop teres  for  ourselves,  making 
each  one  larger  than  that  preceding.  But, 
to  our  astonishment,  we  found  that  the 
larger  the  "bat"  the  less  it  flew.  Wejlid 
noMaixDw^tlial^^^nachir^^  only 

twicejhe  Imear  dimensions  of  another 
wouldrgguire^ightjtimes  the  power.  We 
finally  became  discouragedTandreturned 
to  kite-flying,  a  sport  to  which  we  had  de- 
voted so  much  attention  that  we  were 
regarded  as  experts.  But  as  we  became 
older  we  had  to  give  up  this  fascinating 
sport  as  unbecoming  to  boys  of  our  ages. 

It  was  not  till  the  news  of  the  sad  death 
of  Lilienthal  reached  America  in  the 


summer  of  1896  that  we  again  gave  more 
than  passing  attention  to  the  subject  of 
flying.  We  then  studied  with  great  in- 
terest Chanute's  "Progress  in  Flying  Ma- 
chines," Langley's  "Experiments  in 
Aerodynamics,"  the  "Aeronautical  An- 
nuals" of  1905,  1906,  and  1907,  and  sev- 
eral pamphlets  published  by  the  Smith- 
sonian Institution,  especially  articles  by 
Lilienthal  and  extracts  from  Mouillard's 
"Empire  of  the  Air."  The  larger  works 
gave  us  a  good  understanding  of  the  na- 
ture of  the  flying  problem,  and  the  diffi- 
culties in  past  attempts  to  solve  it,  while 
Mouillard  and  Lilienthal,  the  great  mis- 
sionaries of  the  flying  cause,  infected  us 
with  their  own  unquenchable  enthusi- 
asm, and  transformed  idle  curiosity  into 
the  active  zeal  of  workers. 

In  the  field  of  aviation  there  were  two 
schools.  The  first,  represented  by  such 
men  as  Professor  Langley  and  Sir  Hiram 
Maxim,  gave  chief  attention  to  power 
flight;  the  second,  represented  by  Lilien- 
thal, Mouillard,  and  Chanute,  to  soaring 
flight.  Our  sympathies  were  with  the 
latter  school,  partly  from  impatience  at 
the  wasteful  extravagance  of  mounting 
delicate  and  costly  machinery  on  wings 
which  no  one  knew  how  to  manage,  and 
partly,  no  doubt,  from  the  extraordinary 
charm  and  enthusiasm  with  which  the 
apostles  of  soaring  flight  set  forth  the 
beauties  of  sailing  through  the  air  on 
fixed  wdngs,  deriving  the  motive  power 
from  the  wind  itself. 

The  balancing  of  a  flyer  may  seem,  at 
first  thought,  to  be  a  very  simple  matter, 
yet  almost  ever>'  experimenter  had  found 
in  this  one  point  which  he  could  not  sat- 
isfactorily master.   Many  diflerent  meth- 


LIBRARV 

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THE 


EARLY 


HISTORY 


O  F 


THE 


AIRPLANE 


ods  were  tried.  Some  experimenters 
placed  the  center  of  gravity  far  below 
the  wings,  in  the  belief  that  the  weight 
would  naturally  seek  to  remain  at  the 
lowest  point.  It  is  true,  that,  like  the 
pendulum,  it  tended  to  seek  the  lowest 
point;  but  also,  like  the  pendulum,  it 
tended  to  oscillate  in  a  manner  destruc- 
tive of  all  stability.  A  more  satisfactory 
system,  especially  for  lateral  balance, 
was  that  of  arranging  the  wings  in  the 
shape  of  a  broad  V,  to  form  a  dihedral 
angle,  with  the  center  low  and  the  wing- 
tips  elevated.  In  theory  this  was  an  au- 
tomatic system,  but  in  practice  it  had  two 
serious  defects:  first,  it  tended  to  keep 
the  machine  oscillating;  and  second,  its 
usefulness  was  restricted  to  calm  air. 

In  a  slightly  modified  form  the  same 
system  was  applied  to  the  fore-and-aft 
balance.  The  main  aeroplane  was  set  at 
a  positive  angle,  and  a  horizontal  tail  at 
a  negative  angle,  while  the  center  of 
gravity  was  placed  far  forward.  As  in 
the  case  of  lateral  control,  there  was  a 
tendency  to  constant  undulation,  and  the 
very  forces  which  caused  a  restoration 
of  balance  in  calms  caused  a  disturbance 
of  the  balance  in  winds.  Notwithstand- 
ing the  known  limitations  of  this  prin- 
ciple, it  had  been  embodied  in  almost 
every  prominent  flying  machine  which 
had  been  built. 

After  considering  the  practical  effect 
of  the  dihedral  principle,  we  reached  the 
conclusion  that  a  flyer  founded  upon  it 
might  be  of  interest  from  a  scientific 
point  of  view,  but  could  be  of  no  value 
in  a  practical  way.  We  therefore  re- 
solved to  try  a  fundamentally  different 
principle.  We  would  arrange  the  ma- 
chine so  that  it  would  not  tend  to  right 
itself.  We  would  make  it  as  inert  as 
possible  to  the  effects  of  change  of  direc- 
tion or  speed,  and  thus  reduce  the  effects 
of  wind-gusts  to  a  minimum.  We  would 
do  this  in  the  fore-and-aft  stability  by 


giving  the  aeroplanes  a  peculiar  shape; 
and  in  the  lateral  balance  by  arching  the 
surfaces  from  tip  to  tip,  just  the  reverse 
of  what  our  predecessors  had  done.  Then 
by  some  suitable  contrivance,  actuated 
by  the  operator,  forces  should  be  brought 
into  play  to  regulate  the  balance. 

Lilienthal  and  Chanute  had  guided  and 
balanced  their  machines,  by  shifting  the 
weight  of  the  operator's  body.  But  this 
method  seemed  to  us  incapable  of  ex- 
pansion to  meet  large  conditions,  be- 
cause the  weight  to  be  moved  and  the 
distance  of  possible  motion  were  limited, 
while  the  disturbing  forces  steadily  in- 
creased, both  with  wing  area  and  with 
wind  velocity.  In  order  to  meet  the 
needs  of  large  machines,  we  wished  to 
employ  some  system  whereby  the  oper- 
ator could  vary  at  will  the  inclination  of 
different  parts  of  the  wings,  and  thus  ob- 
tain from  the  wind  forces  to  restore  the 
balance  which  the  wind  itself  had  dis- 
turbed. This  could  easily  be  done  by 
Using  wings  capable  of  being  warped,  and 
by  supplementary  adjustable  surfaces  in 
the  shape  of  rudders.  As  the  forces  ob- 
tainable for  control  would  necessarily 
increase  in  the  same  ratio  as  the  disturb- 
ing forces,  the  method  seemed  capable  of 
expansion  to  an  almost  unlimited  extent. 
A  happy  device  was  discovered  whereby 
the  apparently  rigid  system  of  super- 
posed surfaces,  invented  by  Wenham, 
and  improved  by  Stringfellow  and 
Chanute,  could  be  warped  in  a  most  un- 
expected way,  so  that  the  aeroplanes 
could  be  presented  on  the  right  and  left 
sides  at  different  angles  to  the  wind. 
This,  with  an  adjustable,  horizontal  front 
rudder,  formed  the  main  feature  of  our 
first  glider. 

The  period  from  1885  to  1900  was  one 
of  unexampled  activity  in  aeronautics, 
and  for  a  time  there  was  high  hope  that 
the  age  of  flying  was  at  hand.  But  Max- 
im, after  spending  $100,000,  abandoned 


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the  work;  the  Ader  machine,  built  at  the 
expense  of  the  French  Government,  was 
a  failure;  Lilienthal  and  Pitcher  were 
killed  in  experiments;  and  Chanute  and 
many  others,  from  one  cause  or  another, 
had  relaxed  their  efforts,  though  it  sub- 
sequently became  known  that  Professor 
Langley  was  still  secretly  at  work  on  a 
machine  for  the  United  States  Govern- 
ment. The  public,  discouraged  by  the 
failures  and  tragedies  just  witnessed, 
considered  flight  bej'ond  the  reach  of 
man,  and  classed  its  adherents  with  the 
inventors  of  perpetual  motion. 

We  began  our  active  experiments  at 
the  close  of  this  period,  in  October,  1900, 
at  Kitty  Hawk,  North  Carolina.  Our  ma- 
chine was  designed  to  be  flown  as  a  kite, 
with  a  man  on  board,  in  winds  from  15 
to  20  miles  an  hour.  But,  upon  trial,  it 
was  found  that  much  stronger  winds 
were  required  to  lift  it.  Suitable  winds 
not  being  plentiful,  we  found  it  neces- 
sary, in  order  to  test  the  new  balancing 
system,  to  fly  the  machine  as  a  kite  with- 
out a  man  on  board,  operating  the  levers 
through  cords  from  the  ground.  This 
did  not  give  the  practice  anticipated,  but 
it  inspired  confidence  in  the  new  system 
of  balance. 

In  the  summer  of  1901  we  became  per- 
sonally acquainted  with  Mr.  Chanute. 
When  he  learned  that  we  were  interested 
in  flying  as  a  sport,  and  not  with  any  ex- 
pectation of  recovering  the  money  we 
were  expending  on  it,  he  gave  us  much 
encouragement.  At  our  invitation,  he 
spent  several  weeks  with  us  at  our  camp 
at  Kill  Devil  Hill,  four  miles  south  of 
Kitty  Hawk,  during  our  experiments  of 
that  and  the  two  succeeding  years.  He 
also  witnessed  one  flight  of  the  power 
machine  near  Dayton,  Ohio,  in  October, 
1904. 

The  machine  of  1901  was  built  with 
the  shape  of  surface  used  by  Lilienthal, 
curved  from  front  to  rear  like  the  seg- 


ment of  a  parabola,  with  a  curvature 
1/12  the  depth  of  its  cord;  but  to  make 
doubly  sure  that  it  would  have  sufficient 
lifting  capacity  when  flown  as  a  kite  in 
15  or  20-mile  winds,  we  increased  the 
area  from  165  square  feet,  used  in  1900, 
to  308  square  feet — a  size  much  larger 
than  Lilienthal,  Pitcher,  or  Chanute  had 
deemed  safe.  Upon  trial,  however,  the 
lifting  capacity  again  fell  very  far  short 
of  calculation,  so  that  the  idea  of  secur- 
ing practice  while  flying  as  a  kite  had  to 
be  abandoned.  Mr.  Chanute,  who  wit- 
nessed the  experiments,  told  us  that  the 
trouble  was  not  due  to  poor  construction 
of  the  machine.  We  saw  only  one  other 
explanation — that  the  tables  of  air-pres- 
sures in  general  use  were  incorrect. 

We  then  turned  to  gliding — coasting 
downhill  on  the  air — ^as  the  only  method 
of  getting  the  desired  practice  in  balanc- 
ing a  machine.  After  a  few  minutes' 
practice  we  were  able  to  make  glides  of 
over  300  feet,  and  in  a  few  days  were 
safely  operating  in  27-mile  winds.  In 
these  experiments  we  met  with  several 
unexpected  phenomena.  We  found  that, 
contrary  to  the  teachings  of  the  books, 
the  center  of  pressure  on  a  curved  sur- 
face traveled  backward  when  the  surface 
was  inclined,  at  small  angles,  more  and 
more  edgewise  to  the  wind.  We  also  dis- 
covered that  in  free  flight,  when  the  wing 
on  one  side  of  the  machine  was  presented 
to  the  wind  at  a  greater  angle  than  the 
one  on  the  other  side,  the  wing  with  the 
greater  angle  descended,  and  the  machine 
turned  in  a  direction  just  the  reverse  of 


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what  we  were  led  to  expect  when  flying 
the  machine  as  a  kite.  The  larger  angle 
gave  more  resistance  to  forward  motion, 
and  reduced  the  speed  of  the  wing  on 
that  side.  The  decrease  in  speed  more 
than  counterbalanced  the  eflect  of  the 
larger  angle.  The  addition  of  a  fixed 
vertical  vane  in  the  rear  increased  the 
trouble,  and  made  the  machine  absolute- 
ly dangerous.  It  was  some  time  before 
a  remedy  was  discovered.  This  consisted 
of  movable  rudders  working  in  conjunc- 
tion with  the  twisting  of  the  wings.  The 
details  of  this  arrangement  are  given  in 
specifications  published  several  years 
ago. 

The  experiments  of  1901  were  far 
from  encouraging.  Although  M  r . 
Chanute  assured  us  that,  both  in  control 
and  in  weight  carried  per  horse-power, 
the  results  obtained  were  better  than 
those  of  any  of  our  predecessors,  yet  we 
saw  that  the  calculations  upon  which  all 
flying  machines  had  been  based  were  un- 
reliable, and  that  all  were  simply  groping 
in  the  dark.  Having  set  out  with  abso- 
lute faith  in  the  existing  scientific  data, 
we  were  driven  to  doubt  one  thing  after 
another,  till  finally,  after  two  years  of 
experiment,  we  cast  it  all  aside,  and  de- 
cided to  rely  entirely  upon  our  own  in- 
vestigations. Truth  and  error  were 
everywhere  so  intimately  mixed  as  to  be 
undistinguishable.  Nevertheless,  the 
time  expended  in  preliminary  study  of 
books  was  not  misspent,  for  they  gave  us 
J  a  good  general  understanding  of  the  sub- 
ject, and  enabled  us  at  the  outset  to  avoid 
effort  in  many  directions  in  which  re- 
sults would  have  been  hopeless. 

The  standard  measurements  of  wind- 
pressures  is  the  force  produced  by  a  cur- 
rent of  air  of  one  mile  per  hour  velocity 
striking  square  against  a  plane  of  one 
square  foot  area.  The  practical  difficul- 
ties of  obtaining  an  exact  measurement 
of  this  force  have  been  great.   The  meas- 


/ 


urements  by  different  recognized  author-  / 
ities  vary  50  i^er  cent.  When  this  simp- 
lest of  measurements  presents  so  great 
difficulties,  what  shall  be  said  of  the 
troubles  encountered  by  those  who  at- 
tempt to  find  the  pressure  at  each  angle 
as  the  plane  is  inclined  more  and  more 
edgewise  to  the  wind?  In  the  eighteenth 
centui*y  the  French  Academy  prepared 
tables  giving  such  information,  and  at  a 
later  date  the  Aeronautical  Society  of 
Great  Britain  made  similar  experiments. 
Manj'  persons  likewise  published  meas- 
urements and  formulas;  but  the  results 
were  so  discordant  that  Professor  Lang- 
ley  undertook  a  new  series  of  measure- 
ments, the  results  of  which  form  the 
basis  of  his  celebrated  work,  "Experi- 
ments in  Aerodynamics."  Yet  a  critical 
examination  of  the  data  upon  which  he 
based  his  conclusions  as  to  the  pressures 
at  small  angles  shows  results  so  various 
as  to  make  many  of  his  conclusions  little 
better  than  guesswork. 

To  work  intelligently,  one  needs  to 
know  the  effects  of  a  multitude  of  varia- 
tions that  could  be  incorporated  in  the 
surfaces  of  flying  machines.  The  pres- 
sures on  squares  are  different  from 
those  on  rectangles,  circles,  triangles,  or 
ellipses;  arched  surfaces  differ  from 
planes,  and  vary  among  themselves  ac- 
cording to  the  depth  of  cur\'ature;  true 
arcs  differ  from  parabolas,  and  the  latter 
differ  among  themselves;  thick  surfaces 
differ  from  thin,  and  surfaces  thicker  in 
one  place  than  another  vary  in  pressure 
when  the  positions  of  maximum  thick- 
ness are  difterent;  some  surfaces  are 
most  efficient  at  one  angle,  others  at  other 
angles.  The  shape  of  the  edge  also  makes 
a  difference,  so  that  thousands  of  com- 
binations are  possible  in  so  simple  a 
thing  as  a  wing. 

We  had  taken  up  aeronautics  merely 
as  a  sport.  We  reluctantly  entered  upon 
the  scientific  side  of  it.    But  we  soon 


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found  the  work  so  fascinating  that  we 
were  drawn  into  it  deeper  and  deeper. 
Two  testing  machines  were  built,  which 
we  believed  would  avoid  the  errors  to 
which  the  measurements  of  others  had 
been  subject.  After  making  preliminary 
measurements  on  a  great  number  of  dif- 
ferent-shaped surfaces,  to  secure  a  gen- 
eral understanding  of  the  subject,  we  be- 
gan systematic  measurements  of  stan- 
dard surfaces,  so  varied  in  design  as  to 
bring  out  the  underlying  causes  of  dif- 
ferences noted  in  their  pressures.  Meas- 
urements were  tabulated  on  nearly  50  of 
these  at  all  angles  from  zero  to  45  de- 
grees at  intervals  of  2i/2  degrees.  Meas- 
urements were  also  secured  showing  the 
effects  on  each  other  when  surfaces  are 
superposed,  or  when  they  follow  one  an- 
other. 

Some  strange  results  were  obtained. 
One  surface,  with  a  heavy  roll  at  the 
front  edge,  showed  the  same  lift  for  all 
angles  from  7I/2  to  45  degrees.  A  square 
plane,  contrary  to  the  measurements  of 
all  our  predecessors,  gave  a  greater  pres- 
sure at  30  degrees  than  at  45  degrees. 
This  seemed  so  anomalous  that  we  were 
almost  ready  to  doubt  our  own  measure- 
ments, when  a  simple  test  was  suggested. 
A  weather-vane,  with  two  planes  attached 
to  the  pointer  at  an  angle  of  80  degrees 
with  each  other,  was  made.  According 
to  our  tables,  such  a  vane  would  be  in 
unstable  equilibrium  when  pointing  di- 
rectly into  the  wind;  for  if  by  chance  the 
wind  should  happen  to  strike  one  plane 
at  39  degrees  and  the  other  at  41  degrees, 
the  plane  with  the  smaller  angle  would 
have  the  greater  pressure,  and  the  pointer 
would  be  turned  still  farther  out  of  the 
course  of  the  wind  until  the  two  vanes 
again  secured  equal  pressures,  which 
would  be  at  approximately  30  and  50  de- 
grees. But  the  vane  performed  in  this 
very  manner.  Further  corroboration  of 
the  tables  was  obtained  in  experiments 


with  the  new  glider  at  Kill  Devil  Hill  the 
next  season. 

In  September  and  October,  1902,  near- 
ly 1,000  gliding  flights  were  made,  sev- 
eral of  whicli  covered  distances  of  over 
600  feet.  Some,  made  against  a  wind  of 
36  miles  an  hour,  gave  proof  of  the  ef-^ 
fectiveness  of  the  devices  for  control. 
With  this  machine,  in  the  autumn  of 
1903,  we  made  a  number  of  flights  in 
which  we  remained  in  the  air  for  over  a 
minute,  often  soaring  for  a  considerable 
time  in  one  spot,  without  any  descent  at 
all.  Little  wonder  that  our  unscientific 
assistant  should  think  the  only  thing 
needed  to  keep  it  indefinitely  in  the  air 
would  be  a  coat  of  feathers  to  make  it 
light! 

With  accurate  data  for  making  calcu- 
lations, and  a  system  of  balance  effective 
in  winds  as  well  as  in  calms,  we  were 
now  in  a  position,  we  thought,  to  build  a 
successful  power-flyer.  The  first  designs 
provided  for  a  total  weight  of  600  lbs.,  in- 
cluding the  operator  and  an  eight  horse- 
power motor.  But,  upon  completion,  the 
motor  gave  more  power  than  had  been 
estimated,  and  this  allowed  150  lbs.  to  be 
added  for  strengthening  the  wings  and 
other  parts.  , 

Our  tables  made  the  designing  of  the 
wings  an  easy  matter,  and  as  screw- 
propellers  are  simply  wings  traveling  in 
a  spiral  course,  we  anticipated  no  trouble 
from  this  source.  W^e  had  thought  of 
getting  the  theory  of  the  screw-propeller 
from  the  marine  engineers,  and  then,  by 
applying  our  tables  of  air-pressures  to 
their  formulas,  of  designing  air-propel-y 
lers  suitable  for  our  purpose.  But  so  far 
as  we  could  learn,  the  marine  engineers 
possessed  only  empirical  formulas,  and 
the  exact  action  of  the  screw-propeller, 
after  a  century  of  use,  was  still  very  ob- 
scure. As  we  were  not  in  a  position  to 
undertake  a  long  series  of  practical  ex- 
periments to  discover  a  propeller  suitable 


THE 


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HISTORY 


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THE 


AIRPLANE 


for  our  machine,  it  seemed  necessary  to 
obtain  such  a  thorough  understanding 
of  the  theory  of  its  reactions  as  would 
enable  us  to  design  them  from  calcula- 
tions alone.  What  at  first  seemed  a  prob- 
lem became  more  complex  the  longer  we 
studied  it.  With  the  machine  moving 
forward,  the  air  flying  backward,  the 
propellers  turning  sidewise,  and  nothing 
standing  still,  it  seemed  impossible  to  find 
a  starting-point  from  which  to  trace  the 
various  simultaneous  reactions.  Con- 
templation of  it  was  confusing.  After 
long  arguments  we  often  found  our- 
selves in  the  ludicrous  position  of  each 
having  been  converted  to  the  other's  side, 
with  no  more  agreement  than  when  the 
discussion  began. 

It  was  not  till  several  months  had 
passed,  and  every  phase  of  the  problem 
had  been  thrashed  over  and  over,  that 
the  various  reactions  began  to  untangle 
themselves.  When  once  a  clear  under- 
standing had  been  obtained  there  was  no 
difficulty  in  designing  suitable  propellers, 
with  proper  diameter,  pitch,  and  area  of 
blade,  to  meet  the  requirements  of  the 
flyer.  High  eflQciency  in  a  screw-propel- 
ler is  not  dependent  upon  any  particular 
or  peculiar  shape;  and  there  is  no  such 
thing  as  a  "best"  screw.  A  propeller  giv- 
ing a  high  dynamic  efficiency  when  used 
upon  one  machine  may  be  almost  worth- 


less when  used  upon  another.  The 
propeller  should  in  every  case  be 
designed  to  meet  the  particular  condi- 
tions of  the  machine  to  which  it  is  to  be 
applied.  Our  first  propellers,  built  en-  . 
tirely  from  calculation,  gave  in  useful  ^ 
work  66  per  cent,  of  the  power  expended. 
This  was  about  one-third  more  than  had 
been  secured  by  Maxim  or  Langley. 

The  first  flights  with  the  power  ma- 
chine were  made  on  December  17,  1903. 
Only  five  persons  besides  ourselves  were 
present.  These  were  Messrs.  John  T. 
Daniels,  W.  S.  Dough,  and  A.  D.  Ether- 
idge,  of  the  Kill  Devil  Life-Saving  Sta- 
tion; Mr.  W.  C.  Brinkley,  of  Manteo;  and 
Mr.  John  Ward,  of  Naghead.  Although 
a  general  invitation  had  been  extended 
to  the  people  living  within  five  or  six 
miles,  not  many  were  willing  to  face  the 
rigors  of  a  cold  December  wind  in  order 
to  see,  as  they  no  doubt  thought,  another 
flying  machine  not  fly.  The  first  flight 
lasted  only  12  seconds,  a  flight  very  mod- 
est compared  with  that  of  birds,  but  it 
was,  nevertheless,  the  first  in  the  history 
of  the  world  in  which  a  machine  carry- 
ing a  man  had  raised  itself  by  its  own 
power  into  the  air  in  free  flight,  had 
saileed  forward  on  a  level  course  without 
reduction  of  speed,  and  had  finally  land- 
ed without  being  wrecked.  The  second 
and  third  flights  were  a  little  longer,  and 
the  fourth  lasted  59  seconds,  covering  a 
distance  of  852  feet  over  the  ground 
against  a  20-mile  wind. 

After  the  last  flight  the  machine  was 
carried  back  to  camp  and  set  down  in 
what  was  thought  to  be  a  safe  place.  But 
a  few  minutes  later,  while  we  were  en- 
gaged in  conversation  about  the  flights,  a 
sudden  gust  of  wind  struck  the  machine, 
and  started  to  turn  it  over.  All  made  a 
rush  to  stop  it,  but  we  were  too  late. 
Mr.  Daniels,  a  giant  in  stature  and 
strength,  was  lifted  off  his  feet,  and  fall- 
ing inside,  between  the  surfaces,  was 


THE 


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THE 


AIRPLANE 


shaken  about  like  a  rattle  in  a  box  as  the 
machine  rolled  over  and  over.  He  finally 
fell  out  upon  the  sand  with  nothing  worse 
than  painful  bruises,  but  the  damage  to 
the  machine  caused  a  discontinuance  of 
experiments. 

In  the  spring  of  1904,  through  the 
kindness  of  Mr.  Torrence  Huffman,  of 
Daj'ton,  Ohio,  we  were  permitted  to  erect 
a  shed,  and  to  continue  experiments,  on 
what  is  known  as  the  Huffman  Prairie, 
at  Simms  Station,  eight  miles  east  of  Day- 
ton. The  new  machine  was  heavier  and 
stronger,  but  similar  to  the  one  flown  at 
Kill  Devil  Hill.  When  it  was  ready  for 
its  first  trial  every  newspaper  in  Dayton 
was  notified,  and  about  a  dozen  represen- 
tatives of  the  Press  were  present.  Our 
only  request  was  that  no  pictures  be 
taken,  and  that  the  reports  be  unsensa- 
tional,  so  as  not  to  attract  crowds  to  our 
experiment  grounds.  There  were  prob- 
ably 50  persons  altogether  on  the  ground. 
When  preparations  had  been  completed 
a  wind  of  only  three  or  four  miles  was 
blowing — insufficient  for  starting  on  so 
short  a  track — but  since  many  had  come 
a  long  way  to  see  the  machine  in  action, 
an  attempt  was  made.  To  add  to  the 
other  difficulty,  the  engine  refused  to 
work  properly.  The  machine,  after  run- 
ning the  length  of  the  track,  slid  off  the 
end  without  rising  into  the  air  at  all. 
Several  of  the  newspaper  men  returned 
the  next  day,  but  were  again  disappoint- 
ed. The  engine  performed  badly,  and 
after  a  glide  of  only  60  feet,  the  machine 
came  to  the  ground.  Further  trial  was 
postponed  till  the  motor  could  be  put  in 
better  running  condition.  The  reporters 
had  now,  no  doubt,  lost  confidence  in  the 
machine,  though  their  reports,  in  kind- 
ness, concealed  it.  Later,  when  they 
heard  that  we  were  making  flights  of  sev- 
eral minutes'  duration,  knowing  that 
longer  flights  had  been  made  with  air- 


ships, and  not  knowing  any  essential  dif- 
ference between  airships  and  flying  ma- 
chines, they  were  but  little  interested. 

We  had  not  been  flying  long  in  1904 
before  we  found  that  the  problem  of 
equilibrium  had  not  as  yet  been  entirely 
solved.  Sometimes,  in  making  a  circle, 
the  machine  would  turn  over  sidewise 
despite  anything  the  operator  could  do, 
although,  under  the  same  conditions  in 
ordinary  straight  flight,  it  could  have 
been  righted  in  an  instant.  In  one  flight, 
in  1905,  while  circling  around  a  honey 
locust  tree  at  a  height  of  about  50  feet, 
the  machine  suddenly  began  to  turn  up 
on  one  wing,  and  took  a  course  toward 
the  tree.  The  operator,  not  relishing  the 
idea  of  landing  in  a  thorn-tree,  attempted 
to  reach  the  ground.  The  left  wing, 
however,  struck  the  tree  at  a  height  of  10 
or  12  feet  from  the  ground  and  carried 
away  several  branches;  but  the  flight, 
which  had  already  covered  a  distance  of 
six  miles,  was  continued  to  the  starting- 
point. 

The  causes  of  these  troubles — too  tech- 
nical for  explanation  here — ^were  not  en- 
tirely overcome  till  the  end  of  Septem- 
ber, 1905.  The  flights  then  rapidly  in- 
creased in  length,  till  experiments  were 
discontinued  after  October  5,  on  account 
of  the  number  of  people  attracted  to  the 
field.  Although  made  on  a  ground  open 
on  every  side,  and  bordered  on  two  sides 
by  much-traveled  thoroughfares,  with 
electric  cars  passing  every  hour,  and  seen 
by  aU  the  people  living  in  the  neighbor- 
hood for  miles  around,  and  by  several 
hundred  others,  yet  these  flights  have 
been  made  by  some  newspapers  the  sub- 
ject of  a  great  "mystery." 

A  practical  flyer  having  been  finally 
realized,  we  spent  the  years  1906  and 
1907  in  constructing  new  machines  and 
in  business  negotiations.  It  was  not  till 
May  of  this  year  that  experiments  (dis- 
continued in  October,  1905)  were  re- 


THE 


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THE 


AIRPLANE 


sumed  at  Kill  Devil  Hill,  North  Carolina. 
The  recent  flights  were  made  to  test  the 
ability  of  our  machine  to  meet  the  re- 
quirements of  a  contract  with  the  United 
States  Government  to  furnish  a  flyer 
capable  of  carrying  two  men  and  sutli- 
cient  fuel  supplies  for  a  flight  of  125 
miles,  with  a  speed  of  40  miles  an  hour. 
The  machine  used  in  these  tests  was  the 
same  one  with  which  the  flights  were 
made  at  Simms  Station  in  1905,  though 
several  changes  had  been  made  to  meet 
present  requirements.  The  operator  as- 
sumed a  sitting  position,  instead  of  lying 
prone,  as  in  1905,  and  a  seat  was  added 
for  a  passenger.  A  larger  motor  was  in- 
stalled, and  radiators  and  gasoline  reser- 
voirs of  larger  capacity  replaced  those 
previously  used.  No  attempt  was  made 
to  make  high  or  long  flights. 

In  order  to  show  the  general  reader  the 
way  in  which  the  machine  operates,  let 
us  fancy  ourselves  ready  for  the  start. 
The  machine  is  placed  upon  a  single-rail 
track  facing  the  wind,  and  is  securely 
fastened  with  a  cable.  The  engine  is  put 
in  motion,  and  the  propellers  in  the  rear 
whir.  You  take  j^our  seat  at  the  center 
of  the  machine  beside  the  operator.  He 
slips  the  cable,  and  you  shoot  forward. 
An  assistant  who  has  been  holding  the 
machine  in  balance  on  the  rail  starts  for- 
ward with  you,  but  before  you  have  gone 
50  feet  the  speed  is  too  great  for  him,  and 
he  lets  go.  Before  reaching  the  end  of 
the  track  the  operator  moves  the  front 
rudder,  and  the  machine  lifts  from  the 
rail  like  a  kite  supported  by  the  pressure 
of  the  air  underneath  it.  The  ground 
under  you  is  at  first  a  perfect  blur,  but  as 
you  rise  the  objects  become  clearer.  At 
a  height  of  100  feet  you  feel  hardly  any 
motion  at  all,  except  for  the  wind  which 
strikes  your  face.  If  you  did  not  take 
the  precaution  to  fasten  your  hat  before 


starting,  you  have  probably  lost  it  by 
this  time.  The  operator  moves  a  lever: 
the  right  wing  rises,  and  the  machine 
swings  about  to  the  left.  You  make  a 
very  short  turn,  yet  you  do  not  feel  the 
sensation  of  being  thrown  from  your 
seat,  so  often  experienced  in  automo- 
bile and  railway  travel.  You  find  your- 
self facing  toward  the  point  from  which 
you  started.  The  objects  on  the  ground 
now  seem  to  be  moving  at  much  higher 
speed,  though  you  perceive  no  change  in 
the  pressure  of  the  wind  on  your  face. 
You  know  then  that  you  are  traveling 
with  the  wind.  When  you  near  the  start- 
ing-point the  operator  stops  the  motor 
while  still  high  in  the  air.  The  machine 
coasts  down  at  an  oblique  angle  to  the 
ground,  and  after  sliding  50  or  100  feet, 
comes  to  rest.  Although  the  machine 
often  lands  when  traveling  at  a  speed  of 
a  mile  a  minute,  you  feel  no  shock  what- 
ever, and  cannot,  in  fact,  tell  the  exact 
moment  at  which  it  first  touched  the 
ground.  The  motor  close  beside  you 
kept  up  an  almost  deafening  roar  during 
the  whole  flight,  yet  in  your  excitement 
you  did  not  notice  it  till  it  stopped! 

Our  experiments  have  been  conducted 
entirelj'  at  our  own  expense.  In  the  be- 
ginning we  had  no  thought  of  recovering 
what  we  were  expending,  which  was  not 
great,  and  was  limited  to  what  we  could 
afford  in  recreation.  Later,  when  a  suc- 
cessful flight  had  been  made  with  a  mo- 
tor, we  gave  up  the  business  in  which  we 
were  engaged,  to  devote  our  entire  time 
and  capital  to  the  development  of  a  ma- 
chine for  practical  uses.  As  soon  as  our 
condition  is  such  that  constant  attention 
to  business  is  not  required,  we  expect  to 
prepare  for  publication  the  results  of  our 
laboratory  experiments,  which  alone 
made  an  early  solution  of  the  flying 
problem  possible. 


liou?  IPe  Made  the  First  Flight 

By  OrvilU  Wright 


.HE  flights  of  the  1902  glider  had 
demonstrated  the  efficiency  of 
our  system  o  f  maintaining 
equihbrium,  and  also  the  accu- 
racy of  the  laboratory  work  upon  which 
the  design  of  the  glider  was  based.  We 
then  felt  that  we  were  prepared  to  calcu- 
late in  advance  the  performance  of  ma- 
chines with  a  degree  of  accuracy  that  had 
never  been  possible  with  the  data  and 
tables  possessed  by  our  predecessors. 
Before  leaving  camp  in  1902  we  were  al- 
ready at  work  on  the  general  design  of  a 
new  machine  which  we  proposed  to 
propel  with  a  motor. 

Immediately  upon  our  return  to  Day- 
ton, we  wrote  to  a  number  of  automobile 
and  motor  builders,  stating  the  purpose 
for  which  we  desired  a  motor,  and  ask- 
ing whether  they  could  furnish  one  that 
would  develop  eight  brake-horsepower, 
with  a  weight  complete  not  exceeding  200 
pounds.  Most  of  the  companies  an- 
swered that  they  were  too  busy  with  their 
regular  business  to  undertake  the  build- 
ing of  such  a  motor  for  us;  but  one  com- 
pany replied  that  they  had  motors  rated 
at  8  horse-power,  according  to  the 
French  system  of  ratings,  which  weighed 
only  135  pounds,  and  that  if  we  thought 
this  motor  would  develop  enough  power 
for  our  purpose  they  would  be  glad  to 
sell  us  one.  After  an  examination  of  the 
particulars  of  this  motor,  from  which 
we  learned  that  it  had  but  a  single  cylin- 
der of  4-inch  bore  and  5-inch  stroke,  we 
were  afraid  it  was  much  over-rated. 
Unless  the  motor  would  develop  a  full  8 
brake-horsepower,  it  would  be  useless 
for  our  purpose. 

Finally  we  decided  to  undertake  the 
building  of  the  motor  ourselves.    We  es- 


timated that  we  could  make  one  of  four 
cylinders  with  4-inch  bore  and  4-inch 
stroke,  weighing  not  over  two  hundred 
pounds,  including  all  accessories.  Our 
only  experience  up  to  that  time  in  the 
building  of  gasoline  motors  had  been  in 
the  construction  of  an  air-cooled  motor, 
5-inch  bore  and  7-incli  stroke,  which  was 
used  to  run  the  machinery  of  our  small 
workshop.  To  be  certain  that  four  cylin- 
ders of  the  size  we  had  adopted  (4"  x  4") 
would  develop  the  necessary  8  horse- 
power, we  first  fitted  them  in  a  tempor- 
ary frame  of  simple  and  cheap  construc- 
tion. In  just  six  weeks  from  the  time  the 
design  was  started,  we  had  the  motor  on 
the  block  testing  its  power.  The  ability 
to  do  this  so  quickly  was  largely  due  to 
the  enthusiastic  and  elTicient  services  of 
Mr.  C.  E.  Taylor,  who  did  all  the  machine 
work  in  our  shop  for  the  first  as  well  as 
the  succeeding  experimental  machines. 
There  was  no  provision  for  lubricating 
either  cylinders  or  bearings  while  this 
motor  was  running.  For  that  reason  it 
was  not  possible  to  run  it  more  than  a 
minute  or  two  at  a  time.  In  these  short 
tests  the  motor  developed  about  nine 
horse-power.  We  were  then  satisfied 
that,  with  proper  lubrication  and  better 
adjustments,  a  little  more  power  could 


THE 


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AIRPLANE 


be  expected.  The  completion  of  the  mo- 
tor according  to  drawing  was,  therefore, 
proceeded  with  at  once. 

While  Mr.  Taylor  was  engaged  with 
this  work,  Wilbur  and  I  were  busy  in 
completing  the  design  of  the  machine 
itself.  The  preliminary  tests  of  the  mo- 
tor having  convinced  us  that  more  than 
8  horse-power  would  be  secured,  we  felt 
free  to  add  enough  weight  to  build  a 
more  substantial  machine  than  we  had 

originally  contemplated. 

****** 

For  two  reasons  we  decided  to  use  two 
propellers.  In  the  first  place  we  could, 
by  the  use  of  two  propellers,  secure  a  re- 
action against  a  greater  quantity  of  air, 
and  at  the  same  time  use  a  larger  pitch 
angle  than  was  possible  with  one  propel- 
ler; and  in  the  second  place  by  having  the 
propellers  turn  in  opposite  direction,  the 
gyroscopic  action  of  one  would  neutral- 
ize that  of  the  other.  The  method  we 
adopted  of  driving  the  propellers  in  op- 
posite directions  by  means  of  chains  is 
now  too  well  known  to  need  description 
here.  We  decided  to  place  the  motor  to 
one  side  of  the  man,  so  that  in  case  of  a 
plunge  headfirst,  the  motor  could  not  fall 
upon  him.  In  our  gliding  experiments 
w^e  had  had  a  numbei-  of  experiences  in 
which  we  had  landed  upon  one  wing,  but 
the  crushing  of  the  wing  had  absorbed 
the  shock,  so  that  we  were  not  uneasy 
about  the  motor  in  case  of  a  landing  of 
that  kind.  To  provide  against  the  ma- 
chine rolling  over  forward  in  landing,  we 
designed  skids  like  sled  runners,  extend- 
ing out  in  front  of  the  main  surfaces. 
Otherwise  the  general  construction  and 
operation  of  the  machine  was  to  be  simi- 
lar to  that  of  the  1902  glider. 

When  the  motor  was  completed  and 
tested,  we  found  that  it  would  develop  16 
horse-power  for  a  few  seconds,  but  that 
the  power  rapidlj^  dropped  till,  at  the  end 
of  a  minute,  it  was  only  12  horse-power. 


Ignorant  of  what  a  motor  of  this  size 
ought  to  develop,  we  were  greatly  pleased 
with  its  performance.  More  experience 
showed  us  that  we  did  not  get  one-half 
of  the  power  we  should  have  had. 

With  12  horse-power  at  our  command, 
we  considered  that  we  could  pennit  the 
weight  of  the  machine  with  operator  to 
rise  to  750  or  800  pounds,  and  still  have 
as  much  surplus  power  as  we  had  orig- 
inally allowed  for  in  the  first  estimate  of 
550  pounds. 

Before  leaving  for  our  camp  at  Kitty 
Hawk  we  tested  the  chain  drive  for  tlie 
propellers  in  our  shop  at  Dayton,  and 
found  it  satisfactory.  We  found,  how- 
ever, that  our  first  propeller  shafts, 
which  were  constructed  of  heavy  gauge 
steel  tubing,  were  not  strong  enough  to 
stand  the  shocks  received  from  a  gaso- 
line motor  with  light  fly  wheel,  although 
they  would  have  been  able  to  ti'ansmit 
three  or  four  times  the  power  uniformly 
applied.  We  therefore  built  a  new  set  of 
shafts  of  heavier  tubing,  which  we  tested 
and  thought  to  be  abundantly  strong. 

We  left  Dayton,  September  23,  and  ar- 
rived at  our  camp  at  Kill  Devil  Hill  on 
Friday,  the  25th.  We  found  there  pro- 
visions and  tools,  which  had  been  ship- 
ped by  freight  several  weeks  in  advance. 
The  building,  erected  in  1901  and  en- 
larged in  1902,  was  found  to  have  been 
blown  by  a  stonn  from  its  foundation 
posts  a  few  months  previously.  While 
we  were  awaiting  the  arrival  of  the  ship- 
ment of  machinery  and  parts  from  Day- 
ton, we  were  busy  putting  the  old  build- 
ing in  repair,  and  erecting  a  new  build- 
ing to  serve  as  a  workshop  for  assemb- 
ling and  housing  the  new  machine. 

Just  as  the  building  was  being  com- 
pleted, the  parts  and  material  for  the  ma- 
chines arrived  simultaneously  with  one 
of  the  worst  storms  that  had  visited  Kitty 
Hawk  in  years.  The  storm  came  on  sud- 
denly, blowing  30  to  40  miles  an  hour. 


w 


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THE 


AIRPLANE 


It  increased  during  the  night,  and  the 
next  day  was  blowing  over  75  miles  an 
hour.  In  order  to  save  the  tar-paper 
roof,  we  decided  it  would  be  necessary 
to  get  out  in  this  wind  and  nail  down 
more  securely  certain  parts  that  were 
especially  exposed.  When  I  ascended 
the  ladder  and  reached  the  edge  of  the 
roof,  the  wind  caught  under  my  large 
coat,  blew  it  up  around  my  head  and 
bound  my  arms  till  I  was  perfectly  help- 
less. Wilbur  came  to  mj'  assistance  and 
held  down  my  coat  while  I  tried  to  drive 
the  nails.  But  the  wind  was  so  strong  I 
could  not  guide  the  hammer  and  succeed- 
ed in  striking  my  fingers  as  often  as  the 
nails. 

The  next  three  weeks  were  spent  in 
setting  the  motor-machine  together.  On 
days  with  more  favorable  winds  we 
gained  additional  experience  in  handling 
a  flyer  bj^  gliding  with  the  1902  machine, 
which  we  had  found  in  pretty  fair  condi- 
tion in  the  old  building,  where  we  had 
left  it  the  year  before. 

Mr.  Chanute  and  Dr.  Spratt,  who  had 
been  guests  in  our  camp  in  1901  and 
1902,  spent  some  time  with  us,  but  neith- 
er one  was  able  to  remain  to  see  the  test 
of  the  motor-machine,  on  account  of  the 
delays  caused  by  trouble  which  devel- 
oped in  the  propeller  shafts. 

While  Mr.  Chanute  was  with  us,  a  good 
deal  of  time  was  spent  in  discussion  of 
the  mathematical  calculations  upon 
which  we  had  based  our  machine.  He 
informed  us  that,  in  designing  machin- 
ery, about  20  per  cent,  was  usually  al- 
lowed for  the  loss  in  the  transmission  of 
powej*.  As  we  had  allowed  only  5  per 
cent.,  a  figure  we  had  arrived  at  by  some 
crude  measurements  of  the  friction  of 
one  of  tlie  cliains  when  carrying  only  a 
very  light  load,  we  were  much  alanned. 
More  than  the  whole  surplus  in  power  al- 
lowed in  our  calculations  would,  accord- 
ing to  Mr.  Ghanute's  estimate,  be  con- 


sumed in  friction  in  the  driving  chains. 
After  Mr.  Ghanute's  departure,  we  sus- 
pended one  of  the  drive  chains  over  a 
sprocket,  hanging  bags  of  sand  on  either 
side  of  the  sprocket  of  a  weight  approx- 
imately equal  to  the  pull  that  would  be 
exerted  on  the  chains  when  driving  the 
propellers.  By  measuring  the  extra 
amount  of  weight  needed  on  one  side  to 
lift  the  weight  on  the  other,  we  calcu- 
lated the  loss  in  transmission.  This  indi- 
cated that  the  loss  of  power  from  this 
source  would  be  only  5  per  cent.,  as  we 
originally  estimated.  But  while  we 
could  see  no  serious  error  in  this  method 
of  determining  the  loss,  we  were  very 
uneasy  until  we  had  a  chance  to  run  the 
propellers  with  the  motor  to  see  whether 
we  could  get  the  estimated  number  of 
turns. 

The  first  run  of  the  motor  on  the  ma- 
chine developed  a  flaw  in  one  of  the 
propeller  shafts  which  had  not  been  dis- 
covered in  the  test  at  Dayton.  The  shafts 
were  sent  at  once  to  Daj'ton  for  repair, 
and  were  not  received  again  until  No- 
vember 20,  having  been  gone  two  weeks. 
We  immediately  put  them  in  the  machine 
and  made  another  test.  A  new  trouble 
developed.  The  sprockets  which  were 
screwed  on  the  shafts,  and  locked  with 
nuts  of  opposite  thread,  persisted  in  com- 
ing loose.  After  many  futile  attempts  to 
get  them  fast,  we  had  to  give  it  up  for 
that  day,  and  went  to  bed  much  discour- 
aged. However,  after  a  night's  rest,  we 
got  up  the  next  morning  in  better  spirits 
and  resolved  to  try  again. 

While  in  the  bicycle  business  we  had 
become  well  acquainted  with  the  use  of 
hard  tire  cement  for  fastening  tires  on 
the  rims.  We  had  once  used  it  success- 
fully in  repairing  a  stop  watch  after  sev- 
eral watchsmiths  had  told  us  it  could  not 
be  repaired.  If  tire  cement  was  good  for 
fastening  the  hands  on  a  stop  watch,  why- 
should  it  not  be  good  for  fastening  the 


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sprockets  on  the  propeller  shaft  of  a  fly- 
ing machine?  We  decided  to  try  it.  We 
heated  the  shafts  and  sprockets,  melted 
cement  into  the  threads,  and  screwed 
them  together  again.  This  trouble  was 
over.    The  sprockets  stayed  fast. 

Just  as  the  machine  was  ready  for  test 
bad  weather  set  in.  It  had  been  disagree- 
ably cold  for  several  weeks,  so  cold  that 
we  could  scarcely  work  on  the  machine 
for  some  days.  But  now  we  began  to 
have  rain  and  snow,  and  a  wind  of  25  to 
30  miles  blew  for  several  days  from  the 
north.  While  we  were  being  delayed  by 
the  weather  we  arranged  a  mechanism  to 
measure  automatically  the  duration  of  a 
flight  from  the  time  the  machine  started 
to  move  forward  to  the  time  it  stopped, 
the  distance  traveled  through  the  air  in 
that  time,  and  the  number  of  revolutions 
made  by  the  motor  and  propeller.  A 
stop  watch  took  the  time;  an  anemo- 
meter measured  the  air  traveled 
through;  and  a  counter  took  the  number 
of  revolutions  made  by  the  propellers. 
The  watch  anemometer  and  revolution 
counter  were  all  automatically  started 
and  stopped  simultaneously.  From  data 
thus  obtained  we  expected  to  prove  or 
disprove  the  accuracy  of  our  propeller 
calculations. 

On  November  28,  while  giving  the  mo- 
tor a  run  indoors,  we  thought  we  again 
saw  something  wrong  with  one  of  the 
propeller  shafts.  On  stopping  the  motor 
we  discovered  that  one  of  the  tubular 
shafts  had  cracked! 

Immediate  preparation  was  made  for 
returning  to  Dayton  to  build  another  set 
of  shafts.    We  decided  to  abandon  the 


use  of  tubes,  as  they  did  not  afford 
enough  spring  to  take  up  the  shocks  of 
premature  or  missed  explosions  of  the 
motor.  Solid  tool-steel  shafts  of  smaller 
diameter  tJian  the  tubes  previouslj'  used 
were  decided  upon.  These  would  allow 
a  certain  amount  of  spring.  The  tubular 
shafts  were  many  times  stronger  than 
would  have  been  necessary  to  transmit 
the  power  of  our  motor  if  the  strains  up- 
on them  had  been  unifonn.  But  the 
large  hollow  shafts  had  no  spring  in  them 
to  absorb  the  unequal  strains. 

Wilbur  remained  in  camp  while  I  went 
to  get  the  new  shafts.  I  did  not  get  back 
to  camp  again  till  Friday,  the  11th  of  De- 
cember. Saturday  afternoon  the  ma- 
chine was  again  ready  for  trial,  but  the 
wind  was  so  light  a  start  could  not  have 
been  made  from  level  ground  with  the 
run  of  only  sixty  feet  permitted  by  our 
monorail  track.  Nor  was  there  enough 
time  before  dark  to  take  the  machine  to 
one  of  the  hills,  where,  by  placing  the 
track  on  a  steep  incline,  sufficient  speed 
could  be  secured  for  starting  in  calm  air. 

Monday,  December  14,  was  a  beautiful 
day,  but  there  was  not  enough  wind  to 
enable  a  start  to  be  made  from  the  level 
ground  about  camp.  We  therefore  de- 
cided to  attempt  a  flight  from  the  side  of 
the  big  Kill  Devil  Hill.  We  had  arranged 
with  the  members  of  the  Kill  Devil  Hill 
Life  Saving  Station,  which  was  located  a 
little  over  a  mile  from  our  camp,  to  in- 
form them  when  we  were  ready  to  make 
the  first  trial  of  the  machine.  We  were 
soon  joined  by  J.  T.  Daniels,  Robert 
Westcott,  Thomas  Beachem,  W.  S.  Dough 
and  Uncle  Benny  O'Neal,  of  the  station, 
who  helped  us  get  the  machine  to  the  hill, 
a  quarter  mile  away.  We  laid  the  track 
150  feet  up  the  side  of  the  hill  on  a  9-de- 
gree  slope.  With  the  slope  of  the  track, 
the  thrust  of  the  propellers  and  the  ma- 
chine starting  directly  into  the  wind,  we 
did  not  anticipate  any  ti'ouble  in  getting 


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up  flying  speed  on  the  60-foot  monorail 
track.  But  we  did  not  feel  certain  the 
operator  could  keep  the  machine  bal- 
anced on  the  track. 

When  the  machine  had  been  fastened 
with  a  wire  to  the  track,  so  that  it  could 
not  start  until  released  by  the  operator, 
and  the  motor  had  been  run  to  make  sure 
that  it  was  in  condition,  we  tossed  up  a 
coin  to  decide  who  should  have  the  first 
trial.  Wilbur  won.  I  took  a  position  at 
one  of  the  wings,  intending  to  help  bal- 
ance the  machine  as  it  ran  down  the 
track.  But  when  the  restraining  wire 
was  slipped,  the  machine  started  off  so 
quickly  I  could  stay  with  it  only  a  few 
feet.  After  a  35  to  40-foot  run  it  lifted 
from  the  rail.  But  it  was  allowed  to  turn 
up  too  much.  It  climbed  a  few  feet, 
stalled,  ^nd  then  settled  to  the  ground 
near  the  foot  of  the  hill,  105  feet  below. 
My  stop  watch  showed  that  it  had  been 
in  the  air  just  3l^  seconds.  In  landing 
the  left  wing  touched  first.  The  machine 
swung  around,  dug  the  skids  into  the 
sand  and  broke  one  of  them.  Several 
other  parts  were  also  broken,  but  the 
damage  to  the  machine  was  not  serious. 
While  the  test  had  shown  nothing  as  to 
whether  the  power  of  the  motor  was  suf- 
ficient to  keep  the  machine  up,  since  the 
landing  was  made  many  feet  below  the 
starting  point,  the  experiment  had  dem- 
onstrated that  the  method  adopted  for 
launching  the  machine  was  a  safe  and 
practical  one.  On  the  whole,  we  were 
much  pleased. 

Two  days  were  consumed  in  making 
repairs,  and  the  machine  was  not  ready 
again  till  late  in  the  afternoon  of  the 
16th.  While  we  had  it  out  on  the  track 
in  front  of  the  building,  making  the  final 
adjustments,  a  stranger  came  along. 
After  looking  at  the  machine  a  few  sec- 
onds he  inquired  what  it  was.  When  we 
told  him  it  was  a  flying  machine  he  asked 
whether  we  intended  to  fly  it.    We  said 


we  did,  as  soon  as  we  had  a  suitable  wind. 
He  looked  at  it  several  minutes  longer 
and  then,  wishing  to  be  courteous,  re- 
marked that  it  looked  as  if  it  would  fly, 
if  it  had  a  "suitable  wind."  We  were 
much  amused,  for,  no  doubt,  he  had  in 
mind  the  recent  75-mile  gale  when  he  re- 
peated our  words,  "a  suitable  wind!" 

During  the  night  of  December  16, 
1903,  a  strong  cold  wind  blew  from  the 
north.  When  we  arose  on  the  morning 
of  the  17th,  the  puddles  of  water,  which 
had  been  standing  about  camp  since  the 
recent  rains,  were  covered  with  ice.  The 
wind  had  a  velocity  of  10  to  12  meters  per 
second  (22  to  27  miles  an  hour).  We 
thought  it  would  die  down  before  long, 
and  so  remained  indoors  the  early  part 
of  the  morning.  But  when  ten  o'clock 
arrived,  and  the  wind  was  as  brisk  as 
ever,  we  decided  that  we  had  better  get 
the  machine  out  and  attempt  a  flight. 
We  hung  out  the  signal  for  the  men  of 
the  life  saving  station.  We  thought  that 
by  facing  the  tlyer  into  a  strong  wind, 
there  ought  to  be  no  trouble  in  launch- 
ing it  from  the  level  ground  about  camp. 
We  realized  the  difficulties  of  flying  in 
so  high  a  wind,  but  estimated  that  the 
added  dangers  in  flight  would  be  partly 
compensated  for  by  the  slower  speed  in 
landing. 

We  laid  the  track  on  a  smooth  stretch 
of  ground  about  one  hundred  feet  north 
of  the  new  building.  The  biting  cold 
wind  made  work  difficult,  and  we  had  to 
warm  up  frequently  in  our  living  room, 
where  we  had  a  good  fire  in  an  impro- 
vised stove  made  of  a  large  carbide  can. 
By  the  time  afl  was  ready,  J.  T.  Daniels, 
W.  S.  Dough  and  A.  D.  Etheridge,  mem- 
bers of  the  Kill  Devil  Life  Saving  Station; 
W.  C.  Brinkley,  of  Manleo,  and  Johnny 
Moore,  a  boy  from  Nag's  Head,  had  ar- 
rived. 

We  had  a  "Richards"  hand  anemo- 
meter with  which  we  measured  the  ve- 


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locity  of  the  wind. ,  Measurements  made 
just  before  starting  the  first  flight  showed 
velocities  of  11  to  12  meters  per  second, 
or  24  to  27  miles  per  hour.  Measure- 
ments made  just  before  the  last  flight 
gave  between  9  and  10  meters  per  sec- 
ond. One  made  just  after  showed  a  little 
over  8  meters.  The  records  of  the  Gov- 
ernment Weather  Bureau  at  Kitty  Hawk 
gave  the  velocity  of  the  wind  between  the 
hours  of  10:30  and  12  o'clock,  the  time 
during  which  the  four  flights  were  made, 
as  averaging  27  miles  at  the  time  of  the 
first  flight  and  24  miles  at  the  time  of  the 
last. 

*****  -0 

Wilbur,  having  used  his  turn  in  the 
unsuccessful  attempt  on  the  14th,  the 
right  to  the  first  trial  now  belonged  to 
me.  After  running  the  motor  a  few  min- 
utes to  heat  it  up,  I  released  the  wire  that 
held  the  machine  to  the  track,  and  the 
machine  started  forward  into  the  wind. 
Wilbur  ran  at  the  side  of  the  machine, 
holding  the  wing  to  balance  it  on  the 
track.  Unlike  the  start  on  the  14th,  made 
in  a  calm,  the  machine,  facing  a  27-mile 
wind,  started  verj'  slowly.  Wilbur  was 
able  to  stay  with  it  till  it  lifted  from  the 
track  after  a  forty-foot  run.  One  of  the 
life  saving  men  snapped  the  camera  for 
us,  taking  a  picture  just  as  the  machine 
had  reached  the  end  of  the  track  and  had 
risen  to  a  height  of  about  two  feet.  The 
slow  forward  speed  of  the  machine  over 
the  ground  is  clearly  shown  in  the  pic- 
lure  by  Wilbur's  attitude.  He  stayed 
along  beside  the  machine  witliout  any 
effort. 

The  course  of  the  flight  up  and  down 
was  exceedingly  erratic,  partly  due  to  the 
irregularity  of  the  air,  and  partly  to  lack 
of  experience  in  handUng  this  machine. 
The  control  of  the  front  rudder  was  difQ- 
cult  on  account  of  its  being  balanced  too 
near  the  center.  This  gave  it  a  tendency 
to  turn  itself  when  started;  so  that  it 


turned  too  far  on  one  side  and  then  too 
far  on  the  other.  As  a  result  the  machine 
would  rise  suddenly  to  about  ten  feet, 
and  then  as  suddenly  dart  for  the  ground. 
A  sudden  dart  when  a  little  over  a  hun- 
dred feet  from  the  end  of  the  track,  or  a 
little  over  120  feet  from  the  point  at 
which  it  rose  into  the  air,  ended  the  flight. 
As  the  velocity  of  the  wind  was  over  35 
feet  per  second  and  the  speed  of  the  ma- 
chine against  this  wind  ten  feet  per  sec- 
ond, the  speed  of  the  machine  relative  to 
the  air  was  over  45  feet  per  second,  and 
the  length  of  the  flight  was  equivalent  to 
a  flight  of  540  feet  made  in  calm  air. 
This  flight  lasted  only  12  seconds,  but  it 
was  nevertheless  the  first  in  the  history 
of  the  world  in  which  a  machine  carrying 
a  man  had  raised  itself  by  its  own  power 
into  the  air  in  full  flight,  had  sailed  for- 
ward without  reduction  of  speed,  and 
had  finally  landed  at  a  point  as  high  as 
that  from  which  it  started. 

****** 

At  twenty  minutes  after  eleven  Wilbur 
tarted  on  the  second  flight.  The  course 
of  this  flight  was  much  like  that  of  the 
first,  very  much  up  and  down.  The 
speed  over  the  ground  was  somewhat 
faster  than  that  of  the  first  flight,  due  to 
the  lesser  wind.  The  duration  of  the 
flight  was  less  than  a  second  longer  than 
the  first,  but  the  distance  covered  was 
about  seventy-five  feet  greater. 

Twenty  minutes  later  the  third  flight 
started.  This  one  was  steadier  than  the 
first  one  an  hour  before.  I  was  proceed- 
ing along  pretty  well  when  a  sudden  gust 
from  the  right  lifted  the  machine  up 
twelve  to  fifteen  feet  and  turned  it  up 
sidewise  in  an  alarming  manner.  It  be- 
gan sliding  ofi"  to  the  left.  I  warped  the 
wings  to  try  to  recover  the  lateral  bal- 
ance and  at  the  same  time  pointed  the 
machine  down  to  reach  the  ground  as 
quickly  as  possible.  The  lateral  control 
was  more  effective  than  I  had  imagined 


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and  before  I  reached  the  ground  the  right 
wing  was  lower  than  the  left  and  struck 
first.  The  time  of  this  flight  was  fifteen 
seconds  and  the  distance  over  the  ground 
a  little  over  200  feet. 

Wilbur  started  the  fourth  and  last 
flight  at  just  12  o'clock.  The  first  few 
hundred  feet  were  up  and  down  as  be- 
fore, but  by  the  time  three  hundred  feet 
had  been  covered,  the  machine  was  un- 
der much  better  control.  The  course  for 
the  next  four  or  five  hundred  feet  had 
but  little  undulation.  However,  when 
out  about  eight  hundred  feet  the  machine 
began  pitching  again,  and,  in  one  of  its 
starts  downward,  struck  the  ground. 
The  distance  over  the  ground  was  meas- 
ured and  found  to  be  852  feet;  the  time 
of  the  flight  59  seconds.  The  frame  sup- 
porting the  front  rudder  was  badly 
broken,  but  the  main  part  of  the  ma- 
chine was  not  injured  at  all.  We  esti- 
mated that  the  machine  could  be  put  in 


condition  for  flight  again  in  a  day  or  two. 
While  we  were  standing  about  discuss- 
ing this  last  flight,  a  sudden  strong  gust 
of  wind  struck  the  machine  and  began 
to  turn  it  over.  Everybody  made  a  rush 
for  it.  Wilbur,  who  was  at  one  end, 
seized  it  in  front,  Mr.  Daniels  and  I,  who 
were  behind,  tried  to  stop  it  behind,  tried 
to  stop  it  by  holding  to  the  rear  uprights. 
All  our  efforts  were  vain.  The  machine 
rolled  over  and  over.  Daniels,  who  had 
retained  his  grip,  was  carried  along  with 
it,  and  was  thrown  about  head  over  heels 
inside  of  the  machine.  Fortunately  he 
was  not  seriously  injured,  though  badly 
bruised  in  falling  about  against  the  mo- 
tor, chain  guides,  etc.  The  ribs  in  the 
surfaces  of  the  machine  were  broken,  the 
motor  injured  and  the  chain  guides  badly 
bent,  so  that  all  possibility  of  further 
flights  with  it  for  that  year  were  at  an 
end. 


u 


Some  Aeronauticdl  Experiments 


By   Wilbur   Wright 


HE  difficulties  which  obstruct 
the  pathway  to  success  in  fly- 
ing machine  construction  are 
of  three  general  classes:  (1) 
Those  which  relate  to  the  construction  of 
the  sustaining  wings.  (2)  Those  which 
relate  to  the  generation  and  application 
of  the  power  required  to  drive  the  ma- 
chine through  the  air.  (3)  Those  relat- 
ing to  the  balancing  and  steering  of  the 
machine  after  it  is  actually  in  flight.  Of 
these  difficulties  two  are  already  to  a  cer- 
tain extent  solved.  Men  already  know 
how  to  construct  wings  or  aeroplanes 
which,  when  driven  through  air  at  suffi- 
cient speed,  will  not  only  sustain  the 
weight  of  the  wings  themselves,  but  also 
that  of  the  engine,  and  of  the  engineer  as 
well.  Men  also  know  how  to  build  en- 
gines and  screws  of  sufficient  lightness 
and  power  to  drive  these  planes  at  sus- 
taining speed.  As  long  ago  as  1893  a  ma- 
chine weighing  8,000  lbs.  demonstrated 
its  power  both  to  lift  itself  from  the 
ground  and  to  maintain  a  speed  of  from 
30  to  40  miles  per  hour;  but  it  came  to 
grief  in  an  accidental  free  flight,  owing 
to  the  inability  of  the  operators  to  bal- 
ance and  steer  it  properly.  This  inability 
to  balance  and  steer  still  confronts  stu- 
dents of  the  flying  problem,  although 
nearly  ten  years  have  passed.  When  this 
one  feature  has  been  worked  out  the  age 
of  flying  machines  will  have  arrived,  for 
all  other  difficulties  are  of  minor  im- 
portance. 

The  person  who  merely  watches  the 
flight  of  a  bird  gathers  the  impression 
that  the  bird  has  nothing  to  think  of  but 
the  flapping  of  its  wings.  As  a  matter  of 
fact,  this  is  a  very  small  part  of  its  men- 
tal labour.  Even  to  mention  all  the 
things  the  bird  must  constantly  keep  in 


mind  in  order  to  fly  securely  through  the 
ail'  would  take  a  very  considerable  trea- 
tise. If  I  take  a  piece  of  paper, 
and  after  placing  it  parallel  with  the 
ground,  quickly  let  it  fall,  it  will  not  set- 
tle steadily  down  as  a  staid,  sensible  piece 
of  paper  ought  to  do,  but  it  insists  on  con- 
travening every  recognized  rule  of  de- 
corum, turning  over  and  darting  hither 
and  thither  in  the  most  erratic  manner, 
much  after  the  style  of  an  untrained 
horse.  Yet  this  is  the  style  of  steed  that 
men  must  learn  to  manage  before  flying 
can  become  an  everyday  sport.  The  bird 
has  learned  this  art  of  equilibrium,  and 
learned  it  so  thoroughly  that  its  skill  is 
not  apparent  to  our  sight.  We  only  learn 
to  appreciate  it  when  we  try  to  imitate  it. 
Now,  there  are  two  ways  of  learning  how 
to  ride  a  fractious  horse:  one  is  to  get  on 
him  and  learn  by  actual  practice  how 
each  motion  and  trick  may  be  best  met; 
the  other  is  to  sit  on  a  fence  and  watch 
the  beast  awhile,  and  then  retire  to  the 
house  and  at  leisure  figure  out  the  best 
way  of  overcoming  his  jumps  and  kicks. 
The  latter  system  is  the  safest;  but  the 
former,  on  the  whole,  turns  out  the  larger 
porportion  of  good  riders.  It  is  very 
much  the  same  in  learning  to  ride  a  flying 
machine;  if  you  are  looking  for  perfect 
safety  you  will  do  well  to  sit  on  a  fence 
and  watch  the  birds;  but  if  you  really 
wish  to  learn  you  must  mount  a  machine 
and  become  acquainted  with  its  tricks 
by  actual  trial. 

****** 

My  own  active  interest  in  aeronautical 
problems  dates  back  to  the  death  of 
Lilienthal  in  1896.  The  brief  notice  of 
his  death  which  appeared  in  the  tele- 
graphic news  at  that  time  aroused  a  pas- 
sive interest  which  had  existed  from  my 


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childhood,  and  led  me  to  take  down  from 
the  shelves  of  our  home  library  a  book 
on    "Animal    Mechanism,"    by    Prof. 
Marey,  which  I  had  already  read  several 
times.    From  this  I  was  led  to  read  more 
modern  works,  and  as  my  brother  soon 
became  equally  interested  with  myself, 
we  soon  passed  from  the  reading  to  the 
thinking,   and   finally   to   the  working 
stage.     It  seemed  to  us  that  the  main 
reason  why  the  problem  had  remained  so 
long  unsolved  was  that  no  one  had  been 
able  to  obtain  any  adequate  practice.   We 
figured  that  Lilienthal  in  five  years  of 
time  had  spent  only  about  five  hours  in 
actual  gliding  through  the  air.    The  won- 
der was  not  that  he  had  done  so  little,  but 
that  he  had  accomplished  so  much.    It 
would  not  be  considered  at  all  safe  for  a 
bicycle  rider  to  attempt  to  ride  through 
a  crowded  city  street  after  only  five 
hours'  practice,  spread  out  in  bits  of  ten 
seconds  each  over  a  period  of  five  years; 
yet  Lilienthal  with  this  brief  practice  was 
remarkably  successful  in  meeting  the 
fluctuations  and  eddies  of  wind  gusts. 
We  thought  that  if  some  method  could  be 
found  by  which  it  would  be  possible  to 
practice  by  the  hour  instead  of  by  the 
second  there  would  be  hope  of  advancing 
the  solution  of  a  very  difficult  problem. 
It  seemed  feasible  to  do  this  by  building 
a  machine  which  would  be  sustained  at 
a  speed  of  18  miles  per  hour,  and  then 
finding  a  locality  where  winds  of  this  ve- 
locity were  common.    With  these  condi- 
tions a  rope  attached  to  the  machine  to 
keep  it  from  floating  backward  would 
answer  very  nearly  the  same  purpose  as 
a  propeller  driven  by  a  motor,  and  it 
would  be  possible  to  practice  by  the  hour, 
and  without  any  serious  danger,  as  it 
would  not  be  necessary  to  rise  far  from 
the  ground,  and  the  machine  would  not 
have  any  forward  motion  at  all.     We 
found,  according  to  the  accepted  tables  of 
air  pressures  on  curved  surfaces,  that  a 


machine  spreading  200  square  feet  of 
wing  surface  would  be  sufficient  for  our 
purpose,  and  that  places  could  easily  be 
found  along  the  Atlantic  coast  where 
winds  of  16  to  25  miles  were  not  at  aU 
uncommon.    When  the  winds  were  low 
it  was  our  plan  to  glide  from  the  tops  of 
sand  hills,  and  when  they  were  sufficient- 
ly strong  to  use  a  rope  for  our  motor  and 
fly  over  one  spot.    Our  next  work  was  to 
draw  up  the  plan  for  a  suitable  machine. 
After  much  study  we  finally  concluded 
that  tails  were  a  source  of  trouble  rather 
than  of  assistance,  and  therefore  we  de- 
cided to  dispense  with  them  altogether. 
It  seemed  reasonable  that  if  the  body  of 
the  operator  could  be  placed  in  a  horizon- 
tal position  instead  of  the  upright,  as  in 
the  machines  of  Lilienthal,  Pitcher  and 
Chanute,  the  wind  resistance  could  be 
very  materially  reduced,  since  only  one 
square  foot  instead  of  five  would  be  ex- 
posed.   As  a  full  half-horse-power  could 
be  saved  by  this  change,  we  arranged  to 
try  at  least  the  horizontal  position.   Then 
the  method  of  control  used  by  Lilienthal, 
which  consisted  in  shifting  the  body,  did 
not  seem  quite  as  quick  or  effective  as  the 
case  required;  so,  after  long  study,  we 
contrived  a  system  consisting  of  two 
large  surfaces  on  the  Chanute  double- 
deck  plan,  and  a  smaller  surface  placed 
a  short  distance  in  front  of  the  main  sur- 
faces in  such  a  position  that  the  action  of 
the  wind  upon  it  would  counterbalance 
the  effect  of  the  travel  of  the  center  of 
pressure  on  the  main  surfaces.     Thus 
changes  in  the  direction  and  velocity  of 
the  wind  would  have  little  disturbing  ef- 
fect, and  the  operator  would  be  required 
to  attend  only  to  the  steering  of  the  ma- 
chine, which  was  to  be  effected  by  curv- 
ing the  foi'ward  surface  up  or  down. 
The  lateral  equilibrium  and  the  steering 
to  right  or  left  was  to  be  attained  by  a 
peculiar  torsion  of  the  main  surfaces, 
which  was  equivalent  to  presenting  one 


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end  of  the  wings  at  a  greater  angle  than 
the  other.  In  the  main  frame  a  few 
changes  were  also  made  in  the  details  of 
construction  and  trussing  employed  by 
Mr.  Chanute.  The  most  important  of 
these  were:  ( 1 )  The  moving  of  the  for- 
ward main  cross-piece  of  the  frame  to 
the  extreme  front  edge;  (2)  the  encasing 
in  the  cloth  of  all  cross-pieces  and  ribs  of 
the  surfaces;  (3)  a  rearrangement  of  the 
wires  used  in  trussing  the  two  surfaces 
together,  which  rendered  it  possible  to 
tighten  all  the  wires  by  simply  shortening 
two  of  them. 

With  these  plans  we  proceeded  in  the 
summer  of  1900  to  Kitty  Hawk,  North 
Carolina,  a  little  settlement  located  on 
the  strip  of  land  that  separates  Albemarle 
Sound  from  the  Atlantic  Ocean.  Owing 
to  the  impossibility  of  obtaining  suitable 
material  for  a  200-square-foot  machine, 
we  were  compelled  to  make  it  only  165 
square  feet  in  area,  which,  according  to 
the  Lilienthal  tables,  would  be  supported 
at  an  angle  of  three  degrees  in  a  wind  of 
about  21  miles  per  hour.  On  the  very 
day  that  the  machine  was  completed  the 
wind  blew  from  25  to  30  miles  per  hour, 
and  we  took  it  out  for  a  trial  as  a  kite. 
We  found  that  while  it  was  supported 
with  a  man  on  it  in  a  wind  of  about  25 
miles,  its  angle  was  much  nearer  20  de- 
grees than  three  degrees.  Even  in  gusts 
of  30  miles  the  angle  of  incidence  did  not 
get  as  low  as  three  degiees,  although  the 
wind  at  this  speed  has  more  than  twice 
the  lifting  power  of  a  21-mile  wind.  As 
winds  of  30  miles  per  hour  are  not  plen- 


tiful on  clear  days,  it  was  at  once  evident 
that  our  plan  of  practicing  by  the  hour, 
day  after  day,  would  have  to  be  post- 
poned. Our  system  of  twisting  the  sur- 
faces to  regulate  the  lateral  balance  was 
tried  and  found  to  be  much  more  effec- 
tive than  shifting  the  operator's  body. 
On  subsequent  days,  when  the  wind  was 
too  light  to  support  the  machine  with  a 
man  on  it,  we  tested  it  as  a  kite,  working 
the  rudders  by  cords  reaching  to  the 
ground.  The  results  were  very  satisfac- 
tory, yet  we  were  well  aware  that  this 
method  of  testing  is  never  wholly  con- 
vincing until  the  results  are  confirmed  by 
actual  gliding  experience. 

We  then  turned  our  attention  to  mak- 
ing a  series  of  actual  measurements  of 
the  lift  and  drift  of  the  machine  under 
various  loads.  So  far  as  we  were  aware, 
this  had  never  previously  been  done  with 
any  full-size  machine.  The  results  ob- 
tained were  most  astonishing,  for  it  ap- 
peared that  the  total  horizontal  pull  of 
the  machine,  wliile  sustaining  a  weight 
of  52  lbs.,  was  only  8.5  lbs.,  which  was 
less  than  had  previously  been  estimated 
for  head  resistance  of  the  framing  alone. 
Making  allowance  for  the  weight  carried, 
it  appeared  that  the  head  resistance  of 
the  framing  was  but  little  more  than  50 
per  cent,  of  the  amount  which  Mr. 
Chanute  had  estimated  as  the  head  re- 
sistance of  the  framing  of  his  machine. 
On  the  other  hand,  it  appeared  sadly  de- 
ficient in  lifting  power  as  compared  with 
the  calculated  lift  of  curved  surfaces  of 
its  size.  This  deficiency  we  supposed 
might  be  due  to  one  or  more  of  the  fol- 
lowing causes: — (1)  That  the  depth  of 
the  curvature  of  our  surfaces  was  insuf- 
ficient, being  only  about  one  in  22,  in- 
stead of  one  in  12.  (2)  That  the  cloth 
used  in  our  wings  was  not  sufficiently  air- 
tight. (3)  That  the  Lilienthal  tables 
might  themselves  be  somewhat  in  error. 
We  decided  to  arrange  our  machine  for 


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the  following  year  so  that  the  depth  of 
the  curvature  of  its  surfaces  could  be 
varied  at  will  and  its  covering  air- 
proofed. 

Our  attention  was  next  turned  to  glid- 
ing, but  no  hill  suitable  for  the  purpose 
could  be  found  near  our  camp  at  Kitty 
Hawk.  This  compelled  us  to  take  the  ma- 
chine to  a  point  four  miles  south,  where 
the  Kill  Devil  sand  hill  rises  from  the  flat 
sand  to  a  height  of  more  than  100  feet. 
Its  main  slope  is  toward  the  northeast, 
and  has  an  inclination  of  10  degrees.  On 
the  day  of  our  arrival  the  wind  blew 
about  25  miles  an  hour,  and  as  we  had 
had  no  experience  at  all  in  gliding,  we 
deemed  it  unsafe  to  attempt  to  leave  the 
ground.  But  on  the  day  following,  the 
wind  having  subsided  to  14  miles  per 
hour,  we  made  about  a  dozen  glides.  It 
had  been  the  original  intention  that  the 
operator  should  run  with  the  machine  to 
obtain  initial  velocity,  and  assume  the 
horizontal  position  only  after  the  ma- 
chine was  in  free  flight.  When  it  came 
time  to  land  he  was  to  resume  the  up- 
right position  and  alight  on  his  feet, 
after  the  style  of  previous  gliding  ex- 
periments. But  in  actual  trial  we  found 
it  much  better  to  employ  the  help  of  two 
assistants  in  starting,  which  the  peculiar 
form  of  our  machine  enabled  us  readily 
to  do;  and  in  landing  we  found  that  it  was 
entirely  practicable  to  land  while  still  re- 
clining in  a  horizontal  position  upon  the 
machine.  Although  the  landings  were 
made  while  moving  at  speeds  of  more 
than  20  miles  an  hour,  neither  machine 
nor  operator  suffered  any  injury.  The 
slope  of  the  hiU  was  9.5  deg.,  or  a  drop 
of  one  foot  in  six.  We  found  that  after 
attaining  a  speed  of  about  25  to  30  miles 
with  reference  to  the  wind,  or  10  to  15 
miles  over  the  ground,  the  machine  not 
only  glided  parallel  to  the  slope  of  the 
hill,  but  greatly  increased  its  speed,  thus 
indicating  its  ability  to  glide  on  a  some- 


what less  angle  than  9.5  deg.,  when  we 
should  feel  it  safe  to  rise  higher  from  the 
surface.  The  control  of  the  machine 
proved  even  better  than  we  had  dared  to 
expect,  responding  quickly  to  the  slight- 
est motion  of  the  rudder.  With  these 
glides  our  experiments  for  the  year  1900 
closed.  Although  the  hours  and  hours 
of  practice  we  had  hoped  to  obtain  finally 
dwindled  down  to  about  two  minutes, 
we  were  very  much  pleased  with  the  gen- 
eral results  of  the  trip,  for,  setting  out  as 
we  did  with  almost  revolutionary  the- 
ories on  many  points  and  an  entirely  un- 
tried form  of  machine,  we  considered  it 
quite  a  point  to  be  able  to  return  without 
having  our  pet  theories  completely 
knocked  on  the  head  by  the  hard  logic 
of  experience,  and  our  own  brains 
dashed  out  in  the  bargain.  Everything 
seemed  to  us  to  confirm  the  correctness 
of  our  original  opinions — (1)  that  prac- 
tice is  the  key  to  the  secret  of  flying;  (2) 
that  it  is  practicable  to  assume  the  hori- 
zontal position;  (3)  that  a  smaller  sur- 
face set  at  a  negative  angle  in  front  of 
the  main  bearing  surfaces,  or  wings,  will 
largely  counteract  the  effect  of  the  fore 
and  aft  travel  of  the  center  of  pressure; 
(4)  that  steering  up  and  down  can  be  at- 
tained with  a  rudder  without  moving  the 
position  of  the  operator's  body;  (5)  that 
twisting  the  wings  so  as  to  present  their 
ends  to  the  wind  at  different  angles  is  a 
more  prompt  and  efficient  way  of  main- 
taining lateral  equilibrium  than  that  em- 
ployed in  shifting  the  body  of  the  oper- 
ator of  the  machine. 

When  the  time  came  to  design  our  new 
machine  for  1901  we  decided  to  make  it 
exactly  like  the  previous  machine  in  the- 
ory and  method  of  operation.  But  as  the 
former  machine  was  not  able  to  support 
the  weight  of  the  operator  when  flown 
as  a  kite,  except  in  very  high  winds  and 
at  very  large  angles  of  incidence,  we  de- 
cided to  increase  its  lifting  power.    Ac- 


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corcjingly,  the  curvature  of  the  surfaces 
was  increased  to  one  in  12,  to  confonn  to 
the  shape  on  which  LiUenthal's  table  was 
based,  and  to  be  on  the  safe  side  we  de- 
cided also  to  increase  the  area  of  the  ma- 
chine from  165  square  feet  to  308  square 
feet,  although  so  large  a  machine  had 
never  before  been  deemed  controllable. 
The  Lilienthal  machine  had  an  area  of 
151  square  feet;  that  of  Pilcher,  165 
square  feet;  and  the  Chanute  double- 
decker,  134  square  feet.  As  our  system 
of  control  consisted  in  a  manipulation  of 
the  surfaces  themselves  instead  of  shift- 
ing the  operator's  body,  we  hoped  that 
the  new  machine  would  be  controllable, 
notwithstanding  its  great  size.  Accord- 
ing to  calculations,  it  would  obtain  sup- 
port in  a  wind  of  17  miles  per  hour  with 
an  angle  of  incidence  of  only  three  de- 
grees. 

Our  experience  of  the  previous  year 
having  shown  the  necessity  of  a  suitable 
building  for  housing  the  machine,  we 
erected  a  cheap  frame  building,  16  feet 
wide,  25  feet  long,  and  7  feet  high  at  the 
eaves.  As  our  machine  was  22  feet  wide, 
14  feet  long  (including  the  rudder),  and 
about  6  feet  high,  it  was  not  necessary  to 
take  the  machine  apart  in  any  way  in  or- 
der to  house  it.  Both  ends  of  the  build- 
ing, except  the  gable  parts,  were  made 
into  doors  which  hinged  above,  so  that 
when  opened  they  formed  an  awning  at 
each  end  and  left  an  entrance  the  full 
width  of  the  building.  We  went  into 
camp  about  the  middle  of  July,  and  were 
soon  joined  by  Mr.  E.  C.  Huftaker,  of 
Tennessee,  an  experienced  aeronautical 


investigator  in  the  employ  of  Mr.  Cha- 
nute, by  whom  his  services  were  kindly 
loaned,  and  by  Dr.  A.  G.  Spratt,  of  Penn- 
sylvania, a  young  man  who  has  made 
some  valuable  investigations  of  the 
properties  of  variously  curved  surfaces 
and  the  travel  of  the  center  of  pressure 
thereon.  Early  in  August  Mr.  Chanute 
came  down  from  Chicago  to  witness  our 
experiments,  and  spent  a  week  in  camp 
with  us.  These  gentlemen,  with  my 
brother  and  myself,  formed  our  camping 
party,  but  in  addition  we  had  in  many 
of  our  experiments  the  valuable  assist- 
ance of  Mr.  W.  J.  Tate  and  Mr.  Dan  Tate, 

of  Kitty  Hawk. 

****** 

It  had  been  our  intention  when  build- 
ing the  machine  to  do  most  of  the 
experimenting  in  the  following  manner: 
— When  the  wind  blew  17  miles  an  hour, 
or  more,  we  would  attach  a  rope  to  the 
machine  and  let  it  rise  as  a  kite  with  the 
operator  upon  it.  When  it  should  reach 
a  proper  height  the  operator  would  cast 
off  the  rope  and  glide  down  to  the  ground 
just  as  from  the  top  of  a  hill.  In  this  way 
we  would  be  saved  the  trouble  of  carry- 
ing the  machine  uphill  after  each  glide, 
and  could  make  at  least  10  glides  in  the 
time  required  for  one  in  the  other  way. 
But  when  we  came  to  try  it  we  found  that 
a  wind  of  17  miles,  as  measured  by  Rich- 
ards' anemometer,  instead  of  sustaining 
the  machine  with  its  operator,  a  total 
weight  of  240  lbs.,  at  an  angle  of  inci- 
dence of  three  degrees,  in  reality  would 
not  sustain  the  machine  alone — 100  lbs. 
— at  this  angle.  Its  lifting  capacity 
seemed  scarcely  one-third  of  the  calcu- 
lated amount.  In  order  to  make  sure  that 
this  was  not  due  to  the  porosity  of  the 
cloth,  we  constructed  two  small  experi- 
mental surfaces  of  equal  size,  one  of 
which  was  aii'-proofed  and  the  other  left 
in  its  natural  state;  but  we  could  detect 
no  difference  in  their  lifting  powers. 


80 


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For  a  time  we  were  led  to  suspect  that  the 
lift  of  curved  surfaces  little  exceeded 
that  of  planes  of  the  same  size,  but  fur- 
ther investigation  and  experiment  led  to 
the  opinion  that  (1)  the  anemometer 
used  by  us  over-recorded  the  true  ve- 
locity of  the  wind  by  nearly  15  per  cent.; 
12)  that  the  well-known  Smeaton  coefJi- 
[ent  of  .005  V  ^  for  the  wind  pressure  at 
0  degrees  is  probably  too  great  by  at 
least  20  per  cent.;  (3)  that  Lilienthal's  es- 
timate that  the  pressure  on  a  curved  sur- 
face having  an  angle  of  incidence  of 
three  degrees  equals  .545  of  the  pressure 
at  90  degrees  is  too  large,  being  narly  50 
per  cent,  greater  than  very  recent  experi- 
ments of  our  own  with  a  special  pressure 
testing  machine  indicate;  (4)  that  the  su- 
perposition of  the  surfaces  somewhat  re- 
duced the  lift  per  square  foot,  as  com- 
pared with  a  single  surface  of  equal  area. 
In  gliding  experiments,  however,  the 
amount  of  lift  is  of  less  relative  import- 
ance than  the  ratio  of  lift  to  drift,  as  this 
alone  decides  the  angle  of  gliding  de- 
scent. In  a  plane  the  pressure  is  always 
perpendicular  to  the  surface,  and  the 
ratio  of  lift  to  drift  is  therefore  the  same 
as  that  of  the  cosine  to  the  sine  of  the 
angle  of  incidence.  But  in  curved  sur- 
faces a  verj^  remarkable  situation  is 
found.  The  pressure,  ijistead  of  being 
uniformly  normal  to  the  chord  of  the  arc, 
is  usually  inclined  considerably  in  front 
of  the  perpendicular.  The  result  is  that 
the  lift  is  greater  and  the  drift  less  than 
if  the  pressure  were  normal.  Lilienthal 
was  the  first  to  discover  this  exceedingly 
though  our  measurements  differ  consid- 
erably from  those  of  Lilienthal.  While 
important  fact,  which  is  fully  set  forth 
in  his  book,  "Bird  Flight  the  Basis  of  the 
Flying  Art,"  but  owing  to  some  errors  in 
the  methods  he  used  in  making  measure- 
ments, question  was  raised  by  other  in- 
vestigators not  onlj'  as  to  the  accuracy  of 
Ais  figures,  but  even  as  to  the  existence  of 


any  tangential  force  at  all.  Our  experi- 
ments confirm  the  existence  of  this  force, 
at  Kitty  Hawk  we  spent  much  time  in 
measuring  the  horizontal  pressure  on 
our  unloaded  machine  at  various  angles 
of  incidence.  We  found  that  at  13  de- 
grees the  horizontal  pressure  was  about 
23  lbs.  This  included  not  only  the  drift 
proper,  or  horizontal  component  of  the 
pressure  on  the  side  of  the  surface,  but 
also  the  head  resistance  of  the  framing 
as  well.  The  weight  of  the  machine  at 
the  time  of  this  test  was  about  108  lbs. 
Now,  if  the  pressure  had  been  normal  to 
the  chord  of  the  surface,  the  drift  proper 
would  have  been  to  the  lift  (108  lbs.)  as 
the  sine  of  13  degrees  is  to  the  cosine  of 

13  degrees,  or^?^^^  =  24  +  lbs.;  but 

this  slightly  exceeds  the  total  pull  of  23 
lbs.  on  our  scales.  Therefore,  it  is  evi- 
dent that  the  average  pressure  on  the  sur- 
face, instead  of  being  normal  to  the 
chord,  was  so  far  inclined  toward  the 
front  that  all  the  head  resistance  of  fram- 
ing and  wires  used  in  the  construction 
was  more  than  overcome.    In  a  wind  of 

14  miles  per  hour  resistance  is  by  no 
means  a  negligible  factor,  so  that  tang- 
ential is  evidently  a  force  of  considerable 
value.  In  a  higher  wind,  which  sustained 
the  machine  at  an  angle  of  10  degrees,  the 
pull  on  the  scales  was  18  lbs.  With  the 
pressure  normal  to  the  chord  the  drift 


proper  would  have  been 


.17  X  98 
.98 


17 


lbs.,  so  that,  although  the  higher  wind  ve- 
locity must  have  caused  an  increase  in 


THE 


EARLY 


HISTORY 


O  F 


THE 


AIRPLANE 


the  head  resistance,  the  tangential  force 
still  came  within  one  pound  of  overcom- 
ing it.     After  our  return  from  Kitty 
Hawk  we  began  a  series  of  experiments 
to  accurately  detennine  the  amount  and 
direction  of  the  pressure  produced  on 
curved  surfaces  when  acted  upon  by 
winds  at  the  various  angles  from  zero  to 
90  degrees.    These  experhnents  are  not 
yet  concluded,  but  in  general  they  sup- 
port  Lilienthal  in   the  claim  that  the 
curves  give  pressures  more  favorable  in 
amount  and  direction  than  planes;  but 
we  find  marked  differences  in  the  exact 
values,  especially  at  angles  below  10  de- 
grees.   We  were  unable  to  obtain  direct 
measurements  of  the  horizontal  pres- 
sures of  the  machine  with  the  operator 
on  board,  but  by  comparing  the  distance 
traveled  in  gliding  with  the  vertical  fall, 
it  was  easily  calculated  that  at  a  speed  of 
24  miles  per  hour  the  total  horizontal  re- 
sistance of  our  machine  when  bearing 
the  operator,  amounted  to  40  lbs.,  which 
is  equivalent  to  about  2  1/3  horse-power. 
It  must  not  be  supposed,  however,  that  a 
motor  developing  this  power  would  be 
sufficient  to  drive  a  man-bearing  ma- 
chine.   The  extra  weight  of  the  motor 
would  require  either  a  larger  machine, 
higher  speed,  or  a  greater  angle  of  inci- 
dence in  order  to  support  it,  and  there- 
fore more  power.    It  is  probable,  how- 
ever, that  an  engine  of  six  horse-power, 
weighing  100  lbs.,  would  answer  the  pur- 
pose.   Such  an  engine  is  entirely  practi- 
cable.   Indeed,  working  motors  of  one- 
half  this  weight  per  horse-power  (9  lbs. 
per  horse-power)  have  been  constructed 
by  several  different  builders.    Increasing 
the  speed  of  our  machine  from  24  to  33 


miles  per  hour  reduced  the  total  horizon- 
tal pressure  from  40  to  about  35  lbs.  This 
was  quite  an  advantage  in  gliding,  as  it 
made  it  possible  to  sail  about  15  per  cent, 
further  with  a  given  drop.    However,  it 
would  be  of  little  or  no  advantage  in  re- 
ducing the  size  of  the  motor  in  a  power- 
driven  machine,  because  the  lessened 
thrust  would  be  counter-balanced  by  the 
increased  speed  per  minute.    Some  years 
ago  Professor  Langley  called  attention  to 
the  great  economy  of  tlirust  which  might 
be  obtained  by  using  very  high  speeds, 
and  from  this  many  were  led  to  suppose 
that  high  speed  was  essential  to  success 
in  a  motor-driven  machine.     But  the 
economy  to  which  Professor  Langley 
called  attention  was  in  foot-pounds  per 
mile  of  travel,  not  in  foot  pounds  per 
minute.    It  is  the  foot-pounds  per  min- 
ute that  fixes  the  size  of  the  motor.    The 
probability  is  that  the  first  flying  ma- 
chines will  have  a  relatively  low  speed, 
perhaps  not  much  exceeding  20  miles  per 
hour,  but  the  problem  of  increasing  the 
speed  will  be  much  simpler  in  some  re- 
spects than  that  of  increasing  the  speed 
of  a  steamboat;  for,  whereas  in  the  latter 
case  the  size  of  the  engine  must  increase 
as  the  cube  of  the  speed,  in  the  flying  ma- 
chine, until  extremely  high  speeds  are 
reached,  the  capacity  of  the  motor  in- 
creases in  less  than  simple  ratio;  and 
there  is  even  a  decrease  in  the  fuel  con- 
sumption per  mile  of  travel.    In  other 
words,  to  double  the  speed  of  a  steam- 
ship (and  the  same  is  true  of  the  balloon 
type  of  airship)  eight  times  the  engine 
and  boiler  capacity  would  be  required, 
and  four  times  the  fuel  consumption  per 
mile  of  travel;  while  a  flying  machine 
would    require    engines    of    less    than 
double  the  size,  and  there  would  be  an 
actual  decrease  in  the  fuel  consumption 
per  mile  of  travel.    But  looking  at  the 
matter  conversely,  the  great  disadvan- 
tage of  the  flying  machine  is  apparent; 


8S 


THE 


EARLY 


HISTORY 


O  F 


THE 


AIRPLANE 


for  in  the  latter  no  flight  at  all  is  possible 
unless  the  proportion  of  horse-power  to 
flying  capacity  is  very  high;  but  on  the 
other  hand  a  steamship  is  a  mechanical 
uccess  if  its  ratio  of  horse-power  to  ton- 
nage is  insignificant.  A  flying  machine 
that  would  fly  at  a  speed  of  50  miles  an 
hour  with  engines  of  1 ,000  horsepower 
would  not  be  upheld  by  its  wings  at  all  at 
a  speed  of  less  than  25  miles  an  hour,  and 
nothing  less  than  500  horse-power  could 
drive  it  at  this  speed.  But  a  boat  which 
could  make  40  miles  per  hour  with  en- 
gines of  1,000  horse-power  would  still 
move  four  miles  an  hour  even  if  the  en- 
gines were  reduced  to  one  horse-power. 
The  problems  of  land  and  water  travel 
were  solved  in  the  nineteenth  century, 
because  it  was  possible  to  begin  with 
small  achievements  and  gradually  work 
up  to  our  present  success.  The  flying 
prolem  was  left  over  to  the  twentieth 
century,  because  in  this  case  the  art  must 
be  highly  developed  before  any  flight  of 
any  considerable  duration  at  aU  can  be 
obtained. 

However,  there  is  another  way  of  fly- 
ing which  requires  no  artificial  motor, 
and  many  workers  believe  that  success 
will  first  come  by  this  road.  I  refer  to 
the  soaring  flight,  by  which  the  machine 
is  permanently  sustained  in  the  air  by 
the  same  means  that  are  employed  by 
soaring  birds.  They  spread  their  wings 
to  the  wind,  and  sail  by  the  hour,  with  no 
perceptible  exertion  beyond  that  re- 
quired to  balance  and  steer  themselves. 
What  sustains  them  is  not  definitely 
known,  though  it  is  almost  certain  that  it 
is  a  rising  current  of  air.  But  whether 
it  be  a  rising  current  or  something  else, 
it  is  as  well  able  to  support  a  flying  ma- 
chine as  a  bird,  if  man  once  learns  the  art 
of  utilizing  it.  In  gliding  experiments  it 
has  long  been  known  that  the  rate  of  ver- 
tical descent  is  very  much  retarded,  and 
the  duration  of  the  flight  greatly  pro- 


longed, if  a  strong  wind  blows  up  the  face 
of  the  hill  parallel  to  its  surface.  Our 
machine,  when  gliding  in  still  air,  has  a 
rate  of  vertical  descent  of  nearly  six  feet 
per  second,  while  in  a  wind  blowing  26 
miles  per  hour  up  a  steep  hill  we  made 
glides  in  which  the  rate  of  descent  was 
less  than  two  feet  per  second.  And  dur- 
ing the  larger  part  of  this  time,  while  the 
machine  remained  exactly  in  the  rising 
current,  there  was  no  descent  at  all,  but 
even  a  slight  rise.  If  the  operator  had 
had  sufficient  skill  to  keep  himself  from 
passing  beyond  the  rising  current  he 
would  have  been  sustained  indefinitely 
at  a  higher  point  than  that  from  which 

he  started. 

****** 

In  looking  over  our  experiments  of 
the  past  two  years,  with  models  and  full- 
size  machines,  the  following  points  stand 
out  with  clearness: — 

1.  That  the  lifting  power  of  a  large 
machine,  held  stationary  in  a  wind  at  a 
small  distance  from  the  earth,  is  much 
less  than  the  Lilienthal  table  and  our  own 
laboratory  experiments  would  lead  us  to 
expect.  When  the  machine  is  moved 
through  the  air,  as  in  gliding,  the  discrep- 
ancy seems  much  less  marked. 

2.  That  the  ratio  of  drift  to  lift  in 
well-balanced  surfaces  is  less  at  angles 
of  incidence  of  five  degrees  to  12  de- 
grees than  at  an  angle  of  three  degrees. 

3.  That  in  arched  surfaces  the  center 
of  pressure  at  90  degrees  is  near  the  cen- 
ter of  the  surface,  but  moves  slowly  f or- 


23 


THE 


EARLY 


HISTORY 


O  F 


THE 


AIRPLANE 


ward  as  the  angle  becomes  less,  till  a 
critical  angle  varying  with  the  shape  and 
depth  of  the  curve  is  reached,  after  which 
it  moves  rapidly  toward  the  rear  till  the 
angle  of  no  lift  is  found. 

4.  That  with  similar  conditions  large 
surfaces  may  be  controlled  with  not 
much  greater  difficulty  than  small  ones, 
if  the  control  is  effected  by  manipulation 
of  the  surfaces  themselves,  rather  than 
by  a  movement  of  the  body  of  the  oper- 
ator. 

5.  That  the  head  resistances  of  the 
framing  can  be  brought  to  a  point  much 


below  that  usually  estimated  as  neces- 
sary. 

6.  That  tails,  both  vertical  and  hori- 
zontal, may  with  safety  be  eliminated  in 
gliding  and  other  flying  experiments. 

7.  That  a  horizontal  position  of  the 
operator's  body  may  be  assumed  without 
excessive  danger,  and  thus  the  head  re- 
sistance reduced  to  about  one-fifth  that 
of  the  upright  position. 

8.  That  a  pair  of  superposed,  or  tan- 
dem, surfaces  has  less  lift  in  proportion 
to  drift  than  either  surface  separately, 
even  after  making  allowance  for  weight 
and  head  resistance  of  the  connections. 


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nil  !;l  IN  I  lliill    II  illl    III    III  II  I  Hi  11:1  llll 

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